Compressed air system



Nov. 17, 1942. R. E. WATSON v COMPRESSED AIR SYSTEM Filed July 31, 1941 nv m, w i

m =a H INVENTOR ROBERT E.WAT5ON Lo 4 m' ATTORNEY Patented Nov. 17, 1942 COMPRESSED AIR SYSTEM Robert E. Watson, Swissvale, Pa., assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application July 31, 1941, Serial No. 404,860

8 Claims.

This invention relates to fluid pressure apparatus for fluid pressure control system of the type particularly adapted for controlling electric switches or the like in electric power stations and for pneumatically extinguishing the electric arcs which may result from the operation of the switches.

It is very important that the compressed air apparatus for this service be safe and reliable in order to insure that the switches will operate at the proper time and in the proper manner. It is also important that such apparatus require a minimum amount of space, since the available space in such power stations is usually rather limited.

Air drawn from the atmosphere into a compressor and not previously de-hydrated contains moisture which is delivered to the system with the air compressed by the compressor. Air thus delivered by a compressor will be warm and when it strikes cool parts will cause the moisture therein to be precipitated.

The pressure of water in a system of the above mentioned type is at all times a hazard to the proper functioning of the apparatus, due to cor- 5 roding of valve or switch parts, thus impeding or preventing their normal operation. Therefore, in order to reduce to a safe minimum the moisture content of the air supplied to the system, and to thereby avoid the above mentioned difliculty, it has been found expedient to cool the compressed air substantially to atmospheric temperature before it is passed from the storage volume of the apparatus, such cooling assisting in causing the moisture to be precipitated within a embodying my invention; and Fig. 2 is a similar 7 view with the apparatus turned 90.

As shown in Figs. 1 and 2 of the drawing the apparatus comprises a primary reservoir I, a secondary reservoir 2, an electric motor 3 of the usual well known type for driving an air compressor 4 of any well known type, and as shown, may be of the standard Y type. The apparatus further comprises an aftercooler comprising a cooling unit 6 and a cooling unit I, a shield 8 which encircles the primary reservoir I, and a hood 9 which encloses the motor and compressor.

Considering now more in detail the above mentioned parts of the apparatus, the primary reservoir I and the secondary reservoir 2 may be vertically mounted on a common bed plate l0, as shown in the drawing.

The motor 3 and the compressor 4 are operatively mounted on a channel shaped mounting base H which is secured in any suitable manner to the top of the primary reservoir.

Welded or otherwise secured to the exterior surface of the primary reservoir I is a radially disposed, outwardly extending bracket l2, and diametrically opposite this bracket there is similarly secured to the outer surface of the reservoir two perpendicularly spaced radially disposed, outwardly extending brackets l3 and E4. The bracket I2 is provided at one side with a bolting face i5 and at the opposite side with a similar bolting face and is provided with four perpendicularly spaced passages which extend through the bracket from one bolting face to the other. The brackets I 3 and M are provided with bolting faces l6 and I1, respectively, and with similar bolting faces at the opposite side of each bracket. Each bracket is provided with a passage extending through the bracket from one bolting face to the opposite. The purpose of these brackets will be presently described.

The shield 8, which encircles the primary reservoir I, is removably secured to the brackets l2,

l3 and i4, and at its upper end terminates short of the mounting base H and at its lower end terminates short of the bottom of the reservoir.

Contained within the cylindrical space between the outer surface of the primary reservoir l and the inner surface of the shield 8 are both of the aforementioned cooling units 6 and 1 of the aftercooler. Each unit comprises a fluid conducting conduit which is coiled around the reservoir and is provided with heat radiating pins H5. For the sake of clarity only a few of the heat radiating pins are shown in the drawing.

In the present embodiment of the invention the cooling unit 5 comprises substantially semicircular conduits 2EI, 2| and 22 which are connected together in end to end relationship in the form of a continuous coil by means of brackets 52 and I3, the ends of the conduits being provided with flanges 26 which are secured to the faces able means One end of the coil thus formed is in open communication with the inlet or uppermost passage in the bracket [2 and the opposite end is connected to the reservoir l at a point intermediate the brackets I3 and I4, as shown in the drawing.

The cooling unit 1 is arranged below the unit 6 and comprises three semicircular conduits 23, 24 and 25 which may be identical in every respect with the conduits of the unit 6 and may be connected together in the same manner by the brackets l2 and [4 to form a coil. One end of the coil thus formed is connected to the reservoir I at a point in perpendicular alignment with the brackets 13 and I4 and directly below the bracket 54 while the other end of the coil is in open communication with the third passage from the top of the bracket I2.

The fluid pressure or compressed air discharge passage of the compressor 4 is connected to the inlet or uppermost connection of the bracket II! by means of a pipe or conduit 2'! and the outlet connection from the bracket I2 is connected to the inlet connection of the secondary reservoir 2 by means of a pipe 28. there being a check valve 29 interposed in this conduit between the bracket l2 and the secondary reservoir 2 to prevent back flow of fluid from the secondary reservoir to the primary reservoir.

Leading from the secondary reservoir 2 is a supply pipe 30 in which there is interposed a feed valve device 3| of any suitable structure. The purpose of the feed valve device 3! is to reduce the pressure supplied to the pipe 35 to a lower degree than in the reservoir 2 and which it is desired for use in a system such as shown, described and claimed in my earlier filed application, Serial No. 39l;l31 filed April 30, 1941.

The hood 9 is made of perforated sheet metal so as to permit the free passage of air therethrough for cooling purposes as will presently be described in detail.

Operation Assuming the motor 3 is operating to drive the compressor 4, compressed air is discharged from the compressor to the primary reservoir l- The compressed air discharged by the compressor flows through pipe 21 to the inlet passage of the bracket I2, from whence it flows through the cooling unit 6 to the reservoir 1. From the reservoir I the compressed air flows by way of cooling unit 1 to the outlet connection of bracket l2 and by way of pip 28 to the secondary reservoir 2. The reservoirs l and 2 are thus charged with fluid under pressure by the compressor 4 to a desired degree, such as 250 pounds. Fluid under pressure from the reservoir 2 then flows through the feed valve device 3! to the supply pipe 30, in accordance with the demand for air, the feedvalve reducing the pressure of fluid obtained in said pipe to a desired degree, such as 150 pounds.

The temperature of the air delivered from the compressor is considerably higher than th atmospheric temperature. When hot compressed air passes through the cooling unit 6 it will be cooled to some degree but upon passing through the primary reservoir l and the cooling unit I the temperature of the air delivered to the secondary reservoir will be reduced to approximately atmospheric temperature. This reduction in the temperature of the air delivered to the secondary reservoir is accomplished effectively by the air circulating system which includes the cooling coils of the brackets by means of bolts or other suitand the shield 8 which shield encircles the reservoir l and the cooling units 6 and 1 and forms in effect a stack for conducting cooling air across the cooling coils. It will be noted that the usual ran 34 attached to and forming part of the compressor 4 blows air over the compressor and of course across the upper end of the stack formed by the shield 8, thus diverting warm air rising in the stack away from the compressor through the perforated hood 9. This cooling action causes precipitation of the moisture contained in the compressed air which collects in the cooling units 6 and I and in the reservoir I, thus ensuring against an excessive moisture content in the air delivered to the secondary reservoir 2. The water collected in the cooling units 6 and l flows by gravity to the lowermost portion of the primary reservoir I from whence it may be drained by the use of a drain valve 35 located at the bottom of the reservoir.

It will be noted that the fluid under pressure or compressed air discharged by the compressor 4 is stored in the secondary reservoir 2 at 250 pounds pressure and that it is delivered to the supply pipe 30 at pounds pressure. This is done to further reduce the relative humidity of the air. From actual tests it has been found that this reduction of pressure taken with the cooling operation before described reduce the relative humidity of the air to only 40% of its original value so that the air delivered to the pipe 311 is extremely dry.

Summary From the above description it will, now be apparent that I have provided a simple, compact. reliable and eflicient fluid supply apparatus which de-hydrates the air to such an extent as to render it suitable for use in operating apparatus such as before mentioned or any other pneumatically operated mechanism where dry air is an essential requirement.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A fluid pressure supply apparatus compris ing in combination, a primary reservoir adapted to be charged with fluid under pressure, a compressor for supplying fluid under pressure to said reservoir for charging same, a secondary reservoir adapted to be charged with fluid under pressure from said primary reservoir, means interposed between the compressor and the primary reservoir for cooling the fluid under pressure supplied by said compressor to said primary reservoir, other means interposed between the primary reservoir and the secondary reservoir for cooling the fluid under pressure .supplied from the primary reservoir to the secondary reservoir, both the first mentioned means and the second men tioned means encircling said primary reservoir.

2. A fluid pressure supply apparatus comprising in combination, a primary reservoir adapted to be charged with fluid under pressure, a compressor for supplyingv fluid under pressure to said reservoir for charging same, a secondary reservoir adapted to be charged with fluid under pressure from said primary reservoir, means interposed between the compressor and the primary reservoir for cooling the fluid under pressure supplied by said compressor to said primary reservoir, other means interposed between the primary reservoir and the secondary reservoir for cooling the fluid under pressure supplied from the primary reservoir to the secondary reservoir,

both the first mentioned means and the second mentioned means encircling said primary reservoir, and a fan driven by said compressor for diverting warm air away from both the first and the second mentioned means.

3. A fluid pressure supply apparatus comprising in combination, a primary reservoir adapted to be charged with fluid under pressure, a compressor for supplying fluid under pressure to said reservoir for charging same, a shield spaced away from and encircling said primary reservoir, said shield being open at both the bottom and the top to the atmosphere, a secondary reservoir adapted to be charged with fluid under pressure from said primary reservoir, a conduit disposed in the space between the shield and th primary reservoir through which fluid under pressure is adapted to flow from the compressor to the primary reservoir, another conduit disposed in the space between th shield and the primary reservoir through which fluid under pressure is adapted to flow from the primary reservoir to the secondary reservoir and means for inducing a flow of air through said shield in wiping contact with said primary reservoir and said conduits to extract heat therefrom, said means comprising a fan driven by the compressor.

4. A fluid pressur supply apparatus comprising in combination, a primary reservoir, a secondary reservoir, a compressor unit comprising an electric motor and a fluid compressor operatively mounted on said primary reservoir, a perforated sheet metal hood encircling said compressor unit, a cylindrical shield carried by and encircling said primary reservoir, said shield being spaced away from said primary reservoir and at the upper end terminating short of the compressor unit and at the lower end terminating short of the bottom of the reservoir, a first conduit through which fluid under pressure may flow from said compressor to said primary reservoir, and a second conduit through which fluid under pressure may flow from said primary reservoir to said secondary reservoir, the major portion of said first and second conduits being disposed intermediate said primary reservoir and said shield and being subject to the circulation of air passed through said shield from the bottom to the top thereof.

5. In a fluid compressor supply apparatus having a compressor and a compressor driven fan for cooling the compressor, in combination, a primary reservoir and a secondary reservoir adapted to be charged with fluid under pressure delivered by the compressor, a first cooling coil through which fluid under pressurev is adapted to flow from said compressor to said primary reservoir, a second cooling coil through which fluid under pressure is adapted to flow from said primary to said secondary reservoir, a casing encircling said coils and said primary reservoir, an

air inlet at the bottom of said casing, and an ing in combination, a fluid pressure storage reservoir, brackets secured to the exterior of said reservoir and projecting radially outwardly therefrom, and a cooling coil encircling said reservoir through which fluid under presure may be supplied to said reservoir, said cooling coil comprising a plurality of sections of curved pipe arranged end to end and having the adjacent ends of each two sections abutting and secured to opposite sides of one of said brackets.

7. A fluid pressure supply apparatus comprising in combination, a fluid pressure storage reservoir, a plurality of brackets secured to the exterior of said reservoir and projecting radially outwardly therefrom, a cooling coil encircling said reservoir through which fluid under pressure may be supplied to said reservoir, said cooling coil comprising a plurality of sections of curved pipe arranged end to end and having the adjacent ends of each two sections abutting and received to opposite sides of one of said brackets, and another cooling coil encircling said reservoir through which fluid under pressure may be supplied from said reservoir, said other cooling coil comprising a plurality of sections of curved pipe arranged end to end and having the adjacent ends of each two sections abutting and secured to opposite sides of another of said brackets.

8. A fluid pressure supply apparatus comprising in combination, a fluid pressure storage reservoir, brackets secured to the exterior of said reservoir -,and plrojecting radial-1y outwardly therefrom, a casing encircling said reservoir and carried by said brackets, said casing at one end terminating short of one end of the reservoir and at the opposite end terminating short of the opposite end of the reservoir, a cooling coil comprising a plurality of sections of curved pipe arranged end to end and having the adjacent ends of each two sections abutting and secured to opposite sides of one of said brackets and disposed between the outer wall of the reservoir and the inner wall of the casing through which fluid under pressure may be supplied to said reservoir, and means for inducing a flow of air through said casing in wiping contact with said cooling coil to extract heat therefrom, said means comprising a fan adapted to divert air passed through said casing away from the reservoir.

ROBERT E. WATSON. 

